A team of researchers trying to solve the mystery of aviator Amelia Earhart’s 1937 disappearance said on Friday that underwater video from a Pacific island has revealed a field of man-made debris that could be remnants of her plane.

The footage was collected in July by The International Group for Historic Aircraft Recovery (TIGHAR) during a $2.2 million expedition to Nikumaroro in the Republic of Kiribati.

Unsolved questions about Earhart’s fate have long heightened her legendary status as a pioneering aviator, and TIGHAR’s voyage to seek clues in her disappearance gained interest far beyond the shores of the remote island where the team searched.

The search was plagued by technical issues in what researchers described as challenging ocean conditions off the Nikumaroro reef, where they believe Earhart’s plane landed and was then swept away into the sea.

TIGHAR Director Ric Gillespie said that once his team experienced the harsh conditions, they knew they would not find a “nice intact airplane.” He added the local environment is “very severe” because the ocean “tears things up and tries to bury” them.

The TIGHAR team returned to Honolulu, which is 1,800 miles northeast of Nikumaroro, with no wreckage found. But the researchers said they took hours of underwater video, which they could not view while in Nikumaroro.

TIGHAR said on Friday that one segment of the video shows a field of man-made debris that the group maintains could have come from Earhart’s plane.

Gillespie could not give a size of the man-made objects shown in the video, saying there was nothing in the images with which to compare them for scale.

To the untrained eye, the photo supplied by TIGHAR does not appear to show any evidence of wreckage. But Gillespie said forensic imaging specialist Jeff Glickman of the firm Photek Inc identified the images as a debris field.

“It’s still very early days, but we have man-made objects in a debris field in the place where we’d expect to find it if our theory on the airplane is correct,” Gillespie said.

The TIGHAR announcement comes two days before a Sunday broadcast of a Discovery Channel special on TIGHAR’s expedition.

“We were rushing to get at least some video reviewed so we could show something (on Discovery),” Gillespie said. He added that his group has reviewed only 30 percent of the video they collected.

“We don’t want to oversell this. It’s more evidence. It is where it should be, and that is encouraging,” Gillespie said. “If it does appear to be airplane wreckage, it becomes figuring out how to go back and look at it.”

Earhart and her navigator, Fred Noonan, departed Papua New Guinea July 2, 1937, during Earhart’s quest to circumnavigate the globe along an equatorial route. But they disappeared that day and emergency searches did not locate them.

Hans Van Tilburg, coordinator of the maritime heritage program for the Pacific region of the National Oceanic and Atmospheric Administration, said making a discovery of a decades-old object in the Pacific Ocean is very difficult.

“The Pacific Ocean is a high-energy environment and the aircraft they are looking for is quite fragile,” he said. “Therefore finding something and making identification is very difficult. You are looking for broken pieces.”